The scanners in airports are currently millimeter wave machines. They're fucking useless with insanely high false positive rates, but they don't appear to have any health risks (unlike the backscatter x-ray machines from a decade ago, which I'm sure would be facing cancer lawsuits today if they were still in use).
they were not safe, and they were only approved because the research that said they were safe was done by the manufacturers themselves. They were taken away once academics and other experts showed that the risks were way too high using them
The person is probably extrapolating from the UCSF study that was done (and debunked thoroughly by various governmental and non-governmental organizations).
The complaint about BPA was that it's an estrogen mimic (parts of the human body can react to it as if it were estrogen). If you eat a lot (a whole lot) of soy products, soy can do the same.
BPA has mostly been replaced with BPS ... which is also an estrogen mimic.